In silver halide photographic light-sensitive materials, photosensitive emulsion layers or other layers are often colored for the purpose of absorbing a light of specific wavelength. When it is required to control spectral composition of a light that should enter into a photosensitive emulsion layer, a colored layer is provided at a position remoter from a support than the photosensitive emulsion layer on a photographic light-sensitive material. Such a colored layer is called a filter layer. With the purpose of preventing blur of images, which is caused by reentry of a light scattered when or after it passes through a photosensitive emulsion layer and reflected by an interface between the emulsion layer and a support or a surface of the photosensitive material opposite to the emulsion layer side into the photosensitive emulsion layer, i.e., halation, a colored layer is provided between the photosensitive emulsion layer and the support or on a surface opposite to the photosensitive emulsion layer and the support. Such a colored layer is called antihalation layer. When a multilayer color light-sensitive material is prepared, an antihalation layer may sometimes be provided between the layers. In order to prevent decline of sharpness of images due to light scattering in the photosensitive emulsion layer (this phenomenon is generally called irradiation), the photosensitive emulsion layer may also be colored.
These layers to be colored often consist of hydrophilic colloid, and therefore a water-soluble dye is usually added to the layers for such coloration. Such a dye needs to satisfy the following requirements.    (1) The dye has appropriate spectral absorption depending on a purpose of use.    (2) The day is inactive in terms of photographic chemistry. That is, the dye should not give undesired effects on performances of silver halide photographic light-sensitive materials in a chemical sense, for example, decline of sensitivity, regression of latent image or fog.    (3) The dye is decolorized or removed by dissolution during photographic processes so that it should not leave detrimental coloration on photographic light-sensitive materials after processing.    (4) The dye has superior stability against aging in a solution or a photographic material.
As dyes satisfying these requirements, many kinds of dyes which absorb a visible light or ultraviolet light have been known so far. These dyes are suitable for a purpose of improvement of images in conventional photographic elements sensitized for a wavelength of 700 nm or less. In particular, triarylmethane and oxonol dyes are widely used in relation to the purpose.
It has been desired to develop an antihalation dye or anti-irradiation dye which achieves absorption in an infrared region of spectrum, which is for photographic light-sensitive materials as recently developed recording materials sensitized for infrared wavelengths, e.g., materials for recording outputs of near-infrared lasers. As one of light exposure methods of such photographic light-sensitive materials, for example, so-called scanner type image formation method is known in which an original is scanned, and a photographic light-sensitive material is exposed based on the obtained image signal to form a negative or positive image corresponding to image of the original. In this method, semiconductor lasers are most preferably used as light sources for the scanner type recording method. The semiconductor lasers are small and inexpensive as well as enable easy modulation, and they have a longer lifetime compared with other He—Ne lasers, argon lasers and the like and emit a light in an infrared region. The lasers have an advantage in that, when a photosensitive material having sensitivity in an infrared region is used, a bright safe light can be used, and thus workability for handling is improved.
However, no suitable dye is available which has absorption in an infrared region of spectrum so as to satisfy the aforementioned requirements (1), (2), (3) and (4), in particular, requirements (2) and (3). Therefore, only a few light-sensitive materials having high photosensitivity for an infrared region are available in which halation and irradiation are prevented. Accordingly, at present, the characteristics of the semiconductor lasers having such superior performances as described above cannot fully utilized.
As state of the art concerning cyanines having two carboxyl groups in the 1-position of the indolenine ring, Japanese Patent Laid-open Publication (Kokai) No. (Sho)63-144344 discloses cyanine dyes having two carboxylalkyl groups. However, any cyanine dyes containing an indolenine structure have not been known so far.
As state of the art concerning cyanines having a carboxyl group on the 1-position of the indolenine ring, U.S. Pat. No. 6,002,003 discloses sulfoindolenine cyanine dyes having a carboxyalkyl group. However, the compounds are limited to those wherein the methine group is unsubstituted, and no sulfoindolenine cyanine dye is known which has a substituent on the methine group.
Further, as the art concerning cyanines having an aryl group or a heteroaryl group on the indolenine ring, U.S. Pat. No. 6,004,536 discloses cyanine dyes having a phenyl group, a sulfophenyl group and the like. However, in the cyanine dyes, the substituent on the nitrogen atom at the 1-position is limited to a hydrocarbon group having 7 to 30 carbon atoms, and the patent document fails to disclose any cyanine dyes having a substituent containing 6 or less carbon atoms, in particular, sulfo group and the like, at the 1-position. Moreover, specific examples disclosed in the patent document are limited only to trimethine and pentamethine cyanine dyes, and any heptamethine cyanine dyes having an aryl group or heteroaryl group are not disclosed.